Blockchain-based enactment can guarantee the enforcement of process rules and the preservation of process data. This is achieved without introducing a centrally controlled component-eliminating certain trust concerns in interorganisational processes. However, many issues regarding scalability related metrics like throughput, latency, and cost, but also tradeofs between transparency and confidentiality remain challenging. To address these issues, we aim to investigate state channel technologies for blockchain-based enactment. State channels have been proposed to scale blockchains. They allow to conduct most transactions of-chain, while mostly retaining the core security properties ofered by blockchain. We aim to explore the design space of such channel constructions for process enactment and investigate their relation to other scaling solutions. In doing this, we aim to mitigate some of the current solutions' unfavourable qualities and provide a better understanding of available design options.
CEUR Workshop Proceedings 1Part of this proposal describes work that has already been accepted for publication in [6]. Thus, some descriptions, specifically on research question one, are taken from there. is only used as a settlement layer, reducing the on-chain footprint, while mostly retaining the core security properties ofered by blockchain [ 7].
This idea initially developed from the concept of payment channels (see e.g., [8]). Say, you want to pay an online news site $0.10 per article that you read. You create a channel with the news site, where you lock $5.00 as initial funds (or collateral). Every time you read an article, you exchange an of-chain transaction with the news site, assigning an additional $0.10 to their account. After 32 articles, you decide to close the channel, with the accrued $3.20 assigned to the news site and the remaining $1.80 refunded to your account. This concept can be generalised to state channels [9]. In state channels, participants wishing to transact first agree on a contract governing the rules of the channel and encode these on the blockchain (e.g., in a smart contract). They then conduct of-chain transactions. For each transaction, they agree on the outcome and cryptographically commit to their agreement. Finally, when they have concluded their contract, they submit the final state to the chain. If at any point a participant (supposedly) violates the rules, e.g., attempts to falsify the outcome of a transaction, or become unavailable, the last unanimously agreed transaction is posted to the blockchain. From this state, participants can then safely resume their interaction on the chain, where the blockchain protocol enforces the honest execution of the contract.
While state channels promise to improve scalability related metrics, they come with their own set of challenges. Applying the concept to concrete use cases is challenging. For example, state channel designs require participants to take turns in the protocol to prevent deadlocks. This can become complex in an n-party state channel design [10]. Additionally, state channels introduce new components and significantly increase complexity. Diferent state channel design have been proposed, each with their own set of advantages and drawbacks [7, 10]. Their implications to concrete use cases is not fully understood yet.
We argue that state channels are a fit for inter-organisational processes, where the focus is on a set of interconnected autonomous participants, initiating messages according to some schedule captured in a process model. Furthermore, using model-driven engineering techniques we aim to alleviate the additionally introduced complexity by generating well-tested artefacts from process models. We explore this notion in our first research question: RQ1: How can state channel technology be utilised to achieve favorable tradeofs for blockchain-based process enactment?
The current state of the art in state channel designs focuses on the formalisation and security of protocols for general applications (e.g., [9, 11, 12]); it remains mostly unclear how diferent state channel designs compare in a quantifiable manner. Furthermore, how they compare to existing scaling solutions. It is unclear under what circumstances state channel designs will add benefits to a certain use case and when they will not. Thus, in research question two we ask: RQ2: How do diferent state channel designs compare to other scaling approaches?
In the seminal paper of Weber et al. [
favorable tradeofs for blockchain-based process enactment?
other scaling approaches?
enactment disputes?
potential to design dispute phases, specific to business cases, to incentivise honest participation. Thus, in research question three we ask: RQ3: How can blockchain facilitate the resolution of process enactment disputes? what benefit can state channels add?
Our early results show the value of applying state channel technology to process enactment [6]. In answering our research questions, we envision a holistic approach, improving on the essential tradeofs of blockchain-based enactment.
The current state of the art in blockchain-based business process enactment focuses on
onchain enactment [
The state of the art in state channel2 constructions focuses on the formalisation and security of protocols for general applications (e.g., [9, 11, 12]). More in line with our work, McCorry et al. [21] present a case study investigating the feasibility and applicability of their state channel construction. They present a template for migrating an existing smart contract to a state channel construction. While they present a state channel architecture for n parties, they chose a two-party game as their case. In two-party games, participants can take turns. However, when more participants are involved, a schedule becomes necessary [12]. In our work, we focus on a model-driven approach, where a process model is used to automatically generate the entire channel setup. We aim to use the process control-flow extracted from a 2Hyperledger Fabric uses the terminology of channels for their subnet functionality [20]. The similarity to state channels is weak; like subnets, fabric channels partition the on-chain ledger. State channels construct of-chain channels and use the security guarantees of the on-chain ledger as settlement and dispute resolution layer. process model to naturally enforce a schedule upon the participants. We want to investigate the particularities of enforcing interorganisational processes in channels and evaluate our approach quantitatively and qualitatively in comparison to existing enactment and scaling approaches as well as investigating the design of a process-aware dispute resolution process.
In Table 1 we show the project’s research questions, the corresponding scientific method to approach the question, and the current progress. 3.1. RQ1 How can state channel technology be utilised to achieve favorable tradeofs for blockchain-based process enactment? In question one, we follow a design science approach [22] to determine and evaluate diferent design options for constructing state channels capable of enacting processes. These artefacts will be thoroughly evaluated, both quantitatively (regarding latency, throughput, cost) and qualitatively (regarding blockchain specific security guarantees, see e.g., [ 23, Chapter 1.4]). Our ifrst results show a significant reduction of the on-chain footprint for common settings when enacting processes in state channels [6]. Thus, reducing cost and increasing throughput. Additionally, we find that blockchain specific properties (immutability, non-repudiation, integrity, transparency, and equal rights) largely remain intact—as long as some additional assumptions are met, such as having at least one honest participant per channel.
We believe future designs can build on these results and reduce the on-chain footprint further. For example, by exploring a channel network design, where multiple channels are supported by one contract. Furthermore, we aim to assess more complex process cases where latency is a limiting factor and multiple instances must be scheduled in parallel. Beyond the novel application of state channels to the BPM domain, we expect this RQ will contribute new knowledge regarding the design and application of state channel technology in general. 3.2. RQ2 How do diferent state channel designs compare to other scaling approaches? To answer question two, we aim to perform comprehensive benchmark studies [24]. Our initial results show that state channel-based enactment can considerably reduce transaction cost and increase throughput [6]. But diferent state channel design have been proposed, extending on the original concept, each with their own set of advantages and drawbacks [7, 10].
The question remains, how these diferent designs compare in a qualitative and quantifiable
manner and under what circumstances they add benefits to a use case. Furthermore, it remains
unclear whether state channels can add favourable qualities to other scaling solutions as well.
The enactment of processes, so far, has focused on on-chain enactment, and recommending
the use of permissioned blockchains like Hyperledger Fabric to save cost [
To answer this question, we aim to design dispute phase protocols and evaluate them under certain use case conditions. A more advanced dispute design could, for example, penalise nonconforming participants and remove them from the process by starting a protocol which goal it is to re-bind the role of the participant. We believe there is potential to design advanced dispute processes, specific to process enactment, even improving upon current on-chain enactment approaches. Furthermore, there are potential disputes arising from real world issues, which are not depicted in control-flow. A dispute process could accommodate for such disputes by integrating diferent litigation phases, as, for example, proposed in [ 25].
We propose to investigate state channels for the use in business process enactment. This promises to alleviate some of the inherent scalability issues of blockchain-based execution. Indeed, our initial results show that state channel-based enactment can considerably reduce transaction cost and increase throughput [6]. While our aim is to investigate the foundational aspects of this approach with a focus on scalability first, state channels also reduce the exposure of process data. While confidentiality is breached during a dispute phase, there is potential to design the dispute phase in a confidentiality-preserving manner; for example, by utilising zero-knowledge proofs. While these are usually costly operations, they would only be required in the case of a dispute, making their use more viable [26]. [4] F. Loukil, K. Boukadi, M. Abed, C. Ghedira-Guegan, Decentralized collaborative business process execution using blockchain, WWW 24 (2021) 1645–1663. [5] O. López-Pintado, M. Dumas, L. García-Bañuelos, I. Weber, Interpreted execution of business process models on blockchain, in: EDOC, IEEE, 2019, pp. 206–215. [6] F. Stiehle, I. Weber, Process channels: A new layer for process enactment based on blockchain state channels, in: BPM’23: International Conference on Business Process Management, Utrecht, Netherlands, 2023. In press, accepted. [7] L. Gudgeon, P. Moreno-Sanchez, S. Roos, P. McCorry, A. Gervais, Sok: Layer-two blockchain protocols, in: Financial Cryptography and Data Security, 2020, pp. 201–226. [8] J. Poon, T. Dryja, The bitcoin lightning network: Scalable of-chain instant payments, https://lightning.network/lightning-network-paper.pdf, 2016. Online, Accessed 2023-0329. [9] A. Miller, I. Bentov, S. Bakshi, R. Kumaresan, P. McCorry, Sprites and state channels: Payment networks that go faster than lightning, in: Financial Cryptography and Data Security, 2019, pp. 508–526. [10] L. D. Negka, G. P. Spathoulas, Blockchain state channels: A state of the art, IEEE Access 9 (2021) 160277–160298. [11] S. Dziembowski, S. Faust, K. Hostáková, General state channel networks, in: ACM SIGSAC
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